Eyjafjallajökull Shock Waves

Shake and quake:

Quick explained that in a vulcanian eruption like that going on at Eyjafjallajokull -- the term describes a volcano exhibiting a series of explosive bursts -- you'll see explosions called Plinian events, after the historian Pliny who described the eruption of Vesuvius in 79 AD.

These events are essentially explosive releases of gas. "You have volcanic gases that are held by the magma as it rises toward the surface. Eventually you get to the point where the gases separate from the magma, like popping the top from a soda bottle," Quick explains.

The gases expand rapidly and separate from the magma, causing explosive bursts of tremendous magnitude equivalent to a significant dynamite explosion. As the video shows, the explosion hurls incandescent blobs of lava hundreds of feet into the air -- and cause visible shockwaves.